Aurifil for machine piecing and bobbin for machine quilting
also King Tut on top for machine quilting and So Fine in the bobbin.
I also like silk for hand applique.

I don't like the silk for handwork, it is to hard for me to sew with. Do you all have any tricks to make it behave?

I use Star thread a lot and Connecting Thread thread. There is some Mettler and Guetermann in the bin too. I fluctuate between 50 and 60 wt 3-ply for the most part.

I really like Superior Threads. Check out the web site they also have some great educational tutorials on the site. Very informative. I really like them because they have the recommended needle type and size on the spool. They are pricey but I can attest that the amount of lint coming off is SO MUCH LESS . I never realized how much lint actually comes from the thread.
Also when sewing with a poly or poly blend the static from their thread is much less in the bobbin. Static will cause irregular stitches.
Their metalic thread is truley the best I have ever used.
http://www.superiorthreads.com/
They have a wonderful chart for thread recommendations for specific projects.

I use a lot of dif threads but Essentials is one of my very favorites. I like Guttermann too. I even use Maxi-lock on my Tin Lizzie. Coats is very linty. Superior is good as well as King Tut.

I really like Connecting Thread's thread. I have one of every spool color they make, and several cones as well. Very good quality at priced great.

I bought some of my thread from threadart.com they are a pretty fair price and have all brands

YLI is a brand of thread. Here is their website:
http://www.ylicorp.com/

I haven't purchased from them, but Red Rock Threads seems to be a good discounted source for thread purchases:
http://www.redrockthreads.com/

The Superior Threads website is a great source of information, but their prices seem high to me.

Not sure if you know - King tut - is a type manufactured by Superior Threads.

wow, lots of information, thanks everyone and will follow this thread